Studies on the Mechanism of Proteinuria.

In the chronic active stage of hemorrhagic Bright's disease there are often comparatively long intervals when the amount of functioning kidney tissue decreases very slowly and when there is no marked variation in glomerular permeability. With the patient on a standard regime the urea clearance remains constant, proteinuria fairly so, and blood samples taken under basal conditions with precautions against stasis and effects of posture contain nearly constant percentages of plasma proteins (18). Under such circumstances, some of the factors governing proteinuria may be studied. The amount of protein in the urine, as well as its level in the circulating plasma, seems to depend largely upon the nature and severity of injury to the glomerular capillaries (14). Proteinuria may also be influenced in a moderate degree by the level of protein in the diet (4, 11, 18). In addition to these factors there are apparently others which induce temporary fluctuations in proteinuria. The observations reported here were made in an effort to clarify the problem further. Our results support the concept that the quantity of protein lost in the urine is related to the amount of glomerular filtrate formed and to the rate of production of serum proteins.